SM5L1 데이터 시트보기 (PDF) - Sharp Electronics

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SM5L1

4-Bit Single Chip Microcomputers

Sharp Electronics 

SM5L1/SM5L2/SM5L3

4-Bit Single Chip Microcomputers

Standby Function

A standby function is available which temporarily

stops program execution to conserve power consump-

tion. The state during which a program is in execution

is called the operation mode and the state during which

the execution is temporarily stopped is called the

standby mode.

The standby mode further contains two modes, the

stop mode and the halt mode. The stop mode stops the

system section. In the stop mode, the display (LCD) is

blanked. And the response speed of LCD returning to

the display state (the operation) drops slightly.

The halt mode stops only the system clock genera-

tor circuit, the state of the LCD is retained. This mode

is used to activate the system immediately after a con-

dition causes a release to the operation mode.

To enter the standby mode, select either stop mode

or halt mode, whichever is appropriate. See Figure 23.

During the standby mode, the contents of the RAM

and C flag are retained. The contents of the flags, regis-

ters and output latches shown below are also retained.

• Flags

– IFA flag

– IFD flag

– IME flag

• Registers

– ACC

– X register

– BM, BL register

– SP

– SR

• Output latch registers

– P0 register

– P1 register

– P2 register

A release from the standby mode to the operation

mode is performed by a reset port input, an interrupt

from the nonmaskable INTA and divider. A maskable

interrupt request cannot become a factor in releasing

back to the operation mode. The mask setting is per-

formed with RE register, see Table 1.

CAUTION

When all of P10 to P13 levels are HIGH, the SM5Lx is pro-

grammed to release the standby mode and enter a normally

hardware reset operation (mask option).

TRANSITION FROM THE OPERATION MODE TO

THE STANDBY MODE

The HALT instruction is executed to set the halt

mode and the STOP instruction is executed to set the

stop mode.

Since the interrupt is used to release from the standby

mode, the mode does not transfer to the standby mode

if any of the following conditions are satisfied during exe-

cution of the STOP or HALT instruction.

• RE0 is set and the INTA level is HIGH.

• RE2 is set and the IFD flag is set.

If any of the conditions above are satisfied, the mode

does not transfer to the standby mode even if the

STOP or HALT instruction is executed and the instruc-

tion at the address following that of the STOP or HALT

instruction is executed. Therefore, place the JUMP

instruction which specified step ‘0’ on page 3 to the

location at the address following that of the STOP or

HALT instruction.

OPERATION MODE

RUN HALT

COMMAND

HALT MODE

RELEASE EVENT

STANDBY MODE

HALT MODE

NORMAL

OPERATION

RUN STOP

COMMAND

STOP MODE

RELEASE EVENT

STOP MODE

Figure 23. Operation Shift of Program

5L1-23

18

Microcomputer Data Sheet

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